/*_############################################################################
  _## 
  _##  SNMP4J 2 - PduHandle.java  
  _## 
  _##  Copyright (C) 2003-2011  Frank Fock and Jochen Katz (SNMP4J.org)
  _##  
  _##  Licensed under the Apache License, Version 2.0 (the "License");
  _##  you may not use this file except in compliance with the License.
  _##  You may obtain a copy of the License at
  _##  
  _##      http://www.apache.org/licenses/LICENSE-2.0
  _##  
  _##  Unless required by applicable law or agreed to in writing, software
  _##  distributed under the License is distributed on an "AS IS" BASIS,
  _##  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  _##  See the License for the specific language governing permissions and
  _##  limitations under the License.
  _##  
  _##########################################################################*/
package org.snmp4j.mp;

import java.io.Serializable;

/**
 * The <code>PduHandle</code> class represents an unique key for a SNMP PDU.
 * It uses an unique transaction ID (request ID) to identify the PDUs.
 *
 * @author Frank Fock
 * @version 1.0.3
 * @since 1.0
 */
public class PduHandle implements Serializable {

    private static final long serialVersionUID = -6365764428974409942L;

    public static final int NONE = Integer.MIN_VALUE;
    private int transactionID = NONE;

    /**
     * Creates a <code>PduHandle</code> with a transaction ID set to {@link #NONE}.
     */
    public PduHandle() {
    }

    /**
     * Creates a <code>PduHandle</code> for the supplied transaction ID.
     * @param transactionID
     *    an unqiue transaction ID.
     */
    public PduHandle(int transactionID) {
        setTransactionID(transactionID);
    }

    /**
     * Gets the transaction ID of this handle.
     * @return
     *    the transaction ID.
     */
    public int getTransactionID() {
        return transactionID;
    }

    /**
     * Sets the transaction ID which is typically the request ID of the PDU.
     * @param transactionID
     *    an unqiue transaction ID.
     */
    public void setTransactionID(int transactionID) {
        this.transactionID = transactionID;
    }

    /**
     * Copy all members from the supplied <code>PduHandle</code>.
     * @param other
     *    a PduHandle.
     */
    public void copyFrom(PduHandle other) {
        setTransactionID(other.transactionID);
    }

    /**
     * Indicates whether some other object is "equal to" this one.
     *
     * @param obj the reference object with which to compare.
     * @return <code>true</code> if this object is the same as the obj argument;
     *   <code>false</code> otherwise.
     */
    public boolean equals(Object obj) {
        return (obj instanceof PduHandle) && (transactionID == ((PduHandle) obj).transactionID);
    }

    /**
     * Returns a hash code value for the object.
     *
     * @return a hash code value for this object.
     */
    public int hashCode() {
        return transactionID;
    }

    public String toString() {
        return "PduHandle[" + transactionID + "]";
    }

}
